Abstract
The effect of lactulose on the survival of Lactobacillus rhamnosus VTT E-97800 and on the colon microbiota and its metabolic activity was studied using the Simulator of the Human Intestinal Microbial Ecosystem (SHIME) model. L. rhamnosus VTT E-97800 and lactulose together enhanced the production of butyric acid and decreased ammonium concentration in the model. The numbers of Bacteroides were observed to decrease 2.5-2.0 log 10 cfu/ml during the SHIME experiment. In the subsequent in vivo studies the colonisation of the human colon by L. rhamnosus VTT E-97800 could be confirmed using either RAPD or RiboPrinter™ for the strain identification. RAPD showed that 10-60% more L. rhamnosus VTT E-97800 was detected in lactulose subjects compared with controls after strain feeding was discontinued indicating that lactulose might enhance the survival of the strain in the colon.